Method for producing dilation slots in concrete road surfaces



A. HOLTER sept. e, 1938.

METHOD FOR PRODUGING DILATION SLOTS IN CONCRETE ROAD `SURFACES Filed June 2, 1936 ...L ....2 L.. J1.. ....Z. n". ...cf-an... a c nl u .1 I... 1.... l u l..ln\`\\\\`\`\"\`.

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Patented Sept. 6, 1938 PATENT OFFICE METHOD` FOR PRODUCING DILATION SLOTS IN CONCRETE ROAD SURFACES Alfred Holter, Oslo, Norway Application June 2, 1936, Serial No. 83,153 In Norway June 29, 1935 3 Claims.

1n concrete road surfaces (cement macadam surfaces) it is necessary to provide vertical slots filled with some suitable elastic material at certain intervals, so as to allow a certain freedom of movement to the sections of the road surface during the dilation and contraction taking place owing to changes in temperature. Such elastic boards or strips have to be put in place before the concrete road surface is finished, which means concrete covering is thicker than in its nished state.

In accordance with the present invention the dilation slots are formed -after the mixture of stones and cement sand mortar has taken place and the mixture has been exposed to a preliminary treatment by means of rollers, harrows, plungers or the like by forming a groove in the still soft concrete and inserting in the said groove a board provided with an upwardly directed longitudinal slot.

The height of the board ischosen somewhat less than the thickness of the finished road surface, and in the upwardly directed longitudinal slot of the board there is placed a wedge shaped steel ribbon, which is pressed so far down that its upper edge is Iiush with the upper surface of the unfinished concrete.

During the rolling of the concrete road surface to obtain the final compression of the concrete the said steel ribbon is pressed downwards into the slot of the board, whereby a smooth dilation slot is obtained with the adjacent concrete sections being compressed in exactly the same manner as the rest of the concrete surface.

When the rolling is finished the wedge shaped steel ribbon is rst replaced by an ordinary wooden wedge of the same shape and size, and when the concrete is finally hardened, the said provisional wooden Wedge is removed and the top of the slot is i'illed with an asphalt compound or with a thinner strip of Wood covered with an asphalt compound in order to make the top of 45 the slot watertight.

On the drawing three different stages of the process are illustrated on Figures l, 2 and 3, showling cross sections of a dilation slot and the adjacent concrete.

On all figures the concrete is indicated with l.

Figure l is a section through the slot and the slot board before the finishing. The slot board 2 is put in place and the soft concrete has been packed well about it on both sides. The slot board 2 has an upwardly directed longitudinal slot 3, in

that they must be put in place at a time when the A the upper part of which is inserted the lower edge of the wedge shaped steel ribbon 4.

During the finishing rolling operation the wedge shaped steel ribbon 4 is pressed into the slot 3 as indicated on Figure 2, whereupon the steel ribbon l is removed to be replaced by a strip of wood of the same shape and size, which remains in place until the hardening of the concrete is nished, whereupon the said provisional strip of wood is replaced by an asphalt compound or with a thinner strip of wood 5 covered with a layer of an asphalt compound 6.

1' claim:

l. A method of providing expansion joints in concrete road surfaces, which method comprises forming grooves in the unfinished and unhardened concrete, placing in said grooves means of a height less than the thickness of the nished concrete layer and having an upwardly directed longitudinal slot, placing a wedge-shaped bar with its edge in said upwardly directed slot and with its base substantially flush with the surface of the unlinished concrete, compressing said concrete by rolling and simultaneously pressing the wedge-shaped bar further into said slot so that its surface remains substantially ush with the concrete after the latter has been rolled, removing said bar, and finally, after the concrete has hardened, filling with plastic water-tight material the space previously occupied by said bar.

2. A method of providing expansion joints in concrete road surfaces, which method comprises forming grooves in the unfinished and unhardened concrete, placing in said grooves boards of a height less than the thickness of the nished concrete layer and having an upwardly directed longitudinal slot, placing a wedge-shaped metal bar with its edge in said upwardly directed slot and with its base substantially flush with the surface of the unfinished concrete, compressing said concrete by rolling and simultaneously pressing the wedge-shaped bar further into said slot so that its surface remains substantially ush with the concrete after the latter has been rolled, removing said bar while said boards remain in place, and replacing it with a strip of wood of the same shape, and finally, after the concrete has hardened, removing said strip of wood and filling with plastic water-tight material the space previously occupied by said bar and strip.

3. A method of providing expansion joints in concrete road surfaces, which method comprises forming groovesin the unfinished and unhardened concrete, placing in said grooves boards of a height less than the thickness of the finished crete after the latter has been rolled, removing said bar While said boards remain in place, and finally, after the concrete has hardened, placing a strip of wood covered with a plastic Water-tight material in the space previously occupied by said 5 bar.

ALFRED HOLTER. 

